使用websocket-sharp来创建c#版本的websocket服务

约定不等于承诺〃 2022-06-01 00:48 186阅读 0赞

当前有一个需求，需要网页端调用扫描仪，javascript不具备调用能力，因此需要在机器上提供一个ws服务给前端网页调用扫描仪。而扫描仪有一个c\#版本的API，因此需要寻找一个c\#的websocket库。

java里有大名鼎鼎的netty，通过搜索，c\#可以选择[websocket-sharp][]来实现websocket Server。

### 使用websocket-sharp创建websocket server ###

using System; using WebSocketSharp; using WebSocketSharp.Server; namespace Example { public class Laputa : WebSocketBehavior { protected override void OnMessage (MessageEventArgs e) { var msg = e.Data == "BALUS" ? "I've been balused already..." : "I'm not available now."; Send (msg); } } public class Program { public static void Main (string[] args) { var wssv = new WebSocketServer ("ws://dragonsnest.far"); wssv.AddWebSocketService<Laputa> ("/Laputa"); wssv.Start (); Console.ReadKey (true); wssv.Stop (); } } }

#### Step 1 ####

Required namespace.

using WebSocketSharp.Server;

The `WebSocketBehavior` and `WebSocketServer` 两个类需要引用 `WebSocketSharp.Server` namespace.

#### Step 2 ####

编写处理类，需要继承 `WebSocketBehavior` class.

例如，如果你要创建一个echo Service,

using System; using WebSocketSharp; using WebSocketSharp.Server; public class Echo : WebSocketBehavior { protected override void OnMessage (MessageEventArgs e) { Send (e.Data); } }

再提供一个 chat service,

using System; using WebSocketSharp; using WebSocketSharp.Server; public class Chat : WebSocketBehavior { private string _suffix; public Chat () : this (null) { } public Chat (string suffix) { _suffix = suffix ?? String.Empty; } protected override void OnMessage (MessageEventArgs e) { Sessions.Broadcast (e.Data + _suffix); } }

可以通过继承`WebSocketBehavior`类来自定义Service.

通过重载 `WebSocketBehavior.OnMessage (MessageEventArgs)` 方法, 来处理消息

同时你也可以重载 `WebSocketBehavior.OnOpen ()`, `WebSocketBehavior.OnError (ErrorEventArgs)`, 和 `WebSocketBehavior.OnClose (CloseEventArgs)` 方法,来处理websocket连接事件。

通过`WebSocketBehavior.Send` 方法来给客户端发送消息。

If you would like to get the sessions in the service, you should access the `WebSocketBehavior.Sessions` property (returns a `WebSocketSharp.Server.WebSocketSessionManager`).

The `WebSocketBehavior.Sessions.Broadcast` method can send data to every client in the service.

#### Step 3 ####

创建 `WebSocketServer` 对象.

var wssv = new WebSocketServer (4649); wssv.AddWebSocketService<Echo> ("/Echo"); wssv.AddWebSocketService<Chat> ("/Chat"); wssv.AddWebSocketService<Chat> ("/ChatWithNyan", () => new Chat (" Nyan!"));

#### Step 4 ####

启动 WebSocket server.

wssv.Start ();

#### Step 5 ####

停止 WebSocket server.

wssv.Stop (code, reason);

### 测试Demo ###

`目的`：对外提供一个websocket服务，让网页端的js可以调用扫描仪

#### 服务端代码 ####

class Program { static void Main(string[] args) { var wssv = new WebSocketServer(10086); wssv.AddWebSocketService<ScannerHandler>("/scan"); wssv.Start(); if (wssv.IsListening) { Console.WriteLine("Listening on port {0}, and providing WebSocket services:", wssv.Port); foreach (var path in wssv.WebSocketServices.Paths) Console.WriteLine("- {0}", path); } Console.WriteLine("\nPress Enter key to stop the server..."); Console.ReadLine(); wssv.Stop(); } } public class ScannerHandler : WebSocketBehavior { protected override void OnMessage(MessageEventArgs e) { if(e.Data == "scan") { ScanResult result = ScanerHelper.Scan("D:\\test.jpg"); if (result.Success) { Console.WriteLine("scan success"); Send("scan success"); } else { Send("scan eror"); } } } }

#### 前端代码 ####

javascript代码

var ws; function initWS() { ws = new WebSocket("ws://127.0.0.1:10086/scan"); ws.onopen = function () { console.log("Openened connection to websocket"); }; ws.onclose = function () { console.log("Close connection to websocket"); // 断线重连 initWS(); } ws.onmessage = function (e) { alert(e.data) } } initWS(); function scan() { ws && ws.send('scan'); }

html代码

*  initWS创建连接，支持断线重连
 *  可以调用scan函数，发送scan指令

[websocket-sharp]: https://github.com/sta/websocket-sharp